[BioPython] Updates to Biopython Installation Instructions

[Brad Chapman]

Hi Michael;
Thanks for taking a look at the documentation and the patches! Your
comments are much appreciated.

> > I have updated and expanded the installation instructions for
> > Biopython and separated it out from the main Tutorial
> > documentation... Comments, corrections and other feedback are
> > appreciated as always.
> 
> The following prerequisites appear in the README but are not in the
> installation instructions:
> 
> o psycopg:http://initd.org/software/psycopg/ (optional)
>   This package is only used by BioSQL to access a PostgreSQL database.
> 
> o MySQLdb:http://sourceforge.net/projects/mysql-python (optional)
>   This package is only used by Bio.GFF to access a MySQL database.

I actually wrote these up in the BioSQL installation instructions (since
they are mostly used for this), but I definitely should have had a link
to that documentation. I just added this to the install instructions,
thanks for pointing it out.

> I have patched the installation instructions for MySQLdb (below), but
> I can't check this in right now because I haven't received my password
> for the new machine yet. 

Sweet, thanks for the instructions. Some of this overlapped with what I
already had but I merged them together as you have some better fixes
then I did (I had a braindead fix for the threadsafe thingy, which Jeff
also pointed out to me). It should be all merged (and hopefully still
make sense :-) in the BioSQL docs now.

Did you get CVS sorted? If not, send me a mail and we can get everything
figured. 

> I'm not very familiar with psycopg or BioSQL,
> but last time I checked, the test suite for BioSQL will fail without
> it.

Hmmm... it shouldn't fail -- it should just give one of those import
errors. Is this what it does?

Thanks again for looking at this!
Brad